Pushrod length

-
Greasyfingers

Greasyfingers

Well-Known Member
Joined
Jul 16, 2019
Messages
403
Reaction score
432
Location
Morgan Hill, CA
Yesterday I pulled the valve covers on my 66 273 to adjust the valves. Some of the adjusting screws are almost bottomed out on the rocker.

Now, I built the motor 36 years ago and I'm sure it has less than 50k on it. I remember the machine reground the cam and resurfaced the lifters. I used the original pushrods when I assembled it.

Should I have put longer pushrods in it to compensate for the loss of materials off the reground cam and lifters?
 
273 solid lifter/adjustable rocker pushrods are approximately 7.5"

You may have answered your own questions.

Reground cam has smaller base circles to maintain the lift numbers. The resurfaced solid lifters will shorten them up also.

Were the heads milled .010 ths to clean them up?
 
Were the heads milled .010 ths to clean them up?

I don't remember what was done to the heads at that time. I know I did reuse the original pushrods.

The motor has run fine, but recently the valve train has gotten a little noisier. Hence the decision to adjust the valves.

It was late yesterday, so I didn't examine all the adjuster screws. I'll look at at the rest of the screws in a little bit to see if it's all or just one or two.

I was 16 when I built it, so I "thought" everything was "perfect", especially since it actually fired right up.
 
Well, after pulling the rocker shafts and doing some measuring it looks like I need new pushrods. Number 1 cylinder exhaust pushrod is definitely worn more than the others. The cup end was .010 deeper than the intake push rod. The ball end looked more worn also. I couldn't get and accurate length measurement, because I don't have large enough set of calipers. With a tape measure I can see a bit of a difference in length. I also checked to make sure it wasn't bent and I'm good there.

That was also the valve with the bottomed out adjuster. I guess after 55 years it's time to replace them all.
 
I have no clue what the issue is. The pushrods could be too short or too long reading your first post. The correct pushrod length is measured when the adjuster has 1-2 threads showing. That’s it. If you have more than 2 threads showing the pushrods are too short.
 
Plus the .050 thick rebuilders head gasket. If the cam and lifters look ok. Follow rat bastids advice and order custom pushrods or cut to fit if your comfortable doing that. Mancini has cut to fit. dont need anything special for what you have, just steel.
 
Greasyfingers said:
Yesterday I pulled the valve covers on my 66 273 to adjust the valves. Some of the adjusting screws are almost bottomed out on the rocker.

Now, I built the motor 36 years ago and I'm sure it has less than 50k on it. I remember the machine reground the cam and resurfaced the lifters. I used the original pushrods when I assembled it.

Should I have put longer pushrods in it to compensate for the loss of materials off the reground cam and lifters?
Click to expand...
Assuming you have ball adjusters get you one of these:

Pushrod Length Checkers | Summit Racing.
 
Last edited:
The stock push rods are 7.5. Where can you find longer push rods. I looked every where when i needed some. They jumped to 7.8 but nothing in between. Thats why I went to cut to fit.
 
aaronk785 said:
The stock push rods are 7.5. Where can you find longer push rods. I looked every where when i needed some. They jumped to 7.8 but nothing in between. Thats why I went to cut to fit.
Click to expand...
You’re right, I’m mixing up pushrods. Ball/ball pushrods are the ones easily sourced.:realcrazy:
 
Ive used Smith Brothers for custom length pushrods in the past.
 
Reground Cam and lifters that sat for years? Really! and you want to keep them in? I am not sure I would trust them.
 
He said recently it started making noise. Not disagreeing with you just thought it was a running engine. Which could be a lobe or a lifter.
 
for pushrod length if you are ordering, checkout utube vid "pushrod geometry for engines" by STRAUB. At half lift you want the right length that puts the rocker arm at a right (90 deg) angle to the valve stem for the most area under the curve. EDIT & you want your checking springs to be lighter than the hyd lifter springs as to not depress the lifter springs OR shim a pair of hyd lifters solid at your desired preload amt, say .015". I prefer that as less room for any slack anywhere giving you an incorrect reading.
 
Last edited:
I got a set of comp 7822-16 pushrods from summit today. I got all my adjustment back. My old pushrods must be really worn. The worst one, the cup was .025 deeper than the new ones. I wish I had a large set of calipers, so I could measure them.
 
Keep an eye on them. I had a set and lost three of the balls on the bottom. Pulled them out and and pulled 2 more off the pushrod with channel locks. Hope i just had a bad batch. The old ones were press on later ones are weld on I believe.
 
You must log in or register to reply here.
-

Back
Top